Impedance type pin presence indicator



M. SANDERS ETAL IMPEDANGE TYPE PIN PRESENCE INDICATOR Original Filed April 4. 1957 Feb. 16,1965

'7 Sheets-Sheet l Feb. 16, 1965 M. SANDERS ETAL 3,159,765

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IMPEDANCE TYPE PIN PRESENCE INDICATOR Original Filed April 4, 1957 '7 Sheets-Sheet 7 rp "sega )3y/MM@ @EL ,4free/unf United States Patent O 3,169,765 MPEBANCE TYPE PEN PRESENCE TNDIQATOR Milton Sanders and Howard S. Halpern, Stamford, Conn., assignors to American Machine & Foundry Company, a corporation of New .lersey Original application Apr. 4, 1957, Ser. No. 650,634, now Patent No. 2,980,424, dated Apr. 18, 1961. Divided and this appiication Mar. 24, 1960, Ser. No. 17,283

` 3 Claims. (Ci. 273-52) This invention relates to bowling pin-setting machines and more particularly to completely automatic bowling pin-setting machines in which the operations are electrically controlled in accordance with conditions arising in the course of playing of the bowling games. More particularly the invention relates-to an automatic control of a time delay of a pinspotter by detecting pins invmotion thus shortening the average pinspotter cycle by having time delays of the pinspotter 'variable rather than iixed at the maximum expected duration of pin motion, which is the case in the presently used pinspotters. The invention also includes novel pin fall detecting and signalling mechanism, which indicates the pin fall results after each ball of a frame is rolled. The invention also discloses a control system which prevents the normal, cyclic operation of the machine, and more particularly, the prevention of the operation of its pin-setting and resetting mechanism, when only pin #7 or pin #10 is knocked ot the pin deck of the alley only by the first ball without knocking down any other pins, and allowing the normal operation of the machine if either pin #7 or #l0 is knocked out by the second ball in any given frame. Knocking down of either pin #7 or pin #10 by the second ball, without knocking down any additional pins, can take place only when the first ball is a gutter ball which leaves all pins standing for the second ball, and rolling of the second then knocks out only pin #7 or #10. Under such conditions playing of the frame has been completed and, therefore, the disclosed system permits the normal operation of the pin-setting mechanism. In bowling pin setting machines, one of the main problems is to make all operations as quickly as possible, and to make these operations comply with the rules of the American Bowling Congress. Some automatic bowling machines now in use have a standard delay time for operating pin setting machines to prevent the operation of the machine while any of the pins are in motion. This delay time, as a rule, is equal to the maximum pin motion time that may be encountered in any play. However, there is a much larger number of plays which do not produce any pin motion, such as pin wobble, and, therefore, the maximum delay timebuilt into the present machines is wasteful of time. lThis maximum delay time, as a rule, is derived from the maximum duration of la pin wobble that can take place Without producing a pin fall. The pin wobble may be defined as an oscillation of a bowling pin around its vertical axis. This oscillation may be compared with an oscillation of a pendulum, except that while in the pendulum the center of gravity is below the point of pendulum suspension, in the pin wobble, the center of gravity of the pin is above the point of suspension which, in this case, is the alley door supporting the pin. The pin wobble, as a rule, therefore, is in a single vertical plane with the pin first deilecting to one side and then to the other from its normal vertical position. The energy involved in pin wobble canthe order of 6 to 7 seconds. Since by far the larger numnot exceed that required to tilt the pin from its normal upright position of stable equilibrium which is reached when the center of gravity of the pin is directly above the point of contact of the pin with the alley floor. lf more energy is supplied to the pin than that required to tilt it to its condition of unstable equilibrium, the pin will fall 3,169,765' Patented reis.A 1e, 1965 ice over directly and not wobble. As the pin base becomes worn with use, the base edge becomes more rounded and the point of contact of the pin with the alley floor comes closer to the axis of symmetry of the pin. The position of unstable equilibrium is reached vwith a smaller tilt with the old pins, having worn out bases, than .with the new pins. For a new pin, the maximum duration of pin Wobble is about nine seconds and the maximum peak-to-.peak motion of the pin head is about five inches. The tixed delay built into the pin-spotters is less thannine seconds because it is unnecessary to hold up the operation of 'the machine all full nine seconds even if the maximum possible amplitude wobble does occur. If the pin does not tall within the first' maximum amplitude, it, obviously, will notfall as the amplitudes diminish. However, the operation of the machine cannot be started luntil the amplitude has died down suiciently so as to produce proper engagement of the pin and the pin-sensing and respotting cups and avoid knocking down of the wobbling pin by premature lowering of the respotting cup. Moreover, the players do not wish to see the pinspotter go into operation until all wobble ceases, and the latter consideration, which is of purely psychological nature, requires the iixed time delay to be much longer than that required by` the pin wobble itself. l Usually this xed time delay is of a slight wobble and longer when the wobble is more pronounced.

There are also present, at times, such pin motions as pin spin and pin roll. The path of the rolling pin is approximately an arc of a circle and the pin spin usually is transformed into a pin roll after the spinning pin loses some of its energy. The duration of pin roll is limited by the dimensions of the alley oor and the `presence of other pins. The pin roll and pin spin cease in less time than that required for pin wobble to cease. Therefore, the duration of pin wobble rather than that o'f pin roll or pin spin, determines the maximum delay necessary in pinspotter operation.

VIn order to increase the intelligence of the detecting system still further it is also necessary for such detection system toprovide a pin presence signal in addition to thel With the pin wobble and presence,

'rst ball is a gutter ball, andrwhen both balls are gutterballs.

(4) Direct operationvof the pinfall signal means by the detection system.

The disclosed systems, described briey, are as follows: one of the simplest systems is the system based up'on amplitude modulation of the echo by apinV which is in motion. The simplest version of such system is the one using light as transmitters and photo cells as receivers. Amplitude modulation by pin wobble of the light reiiected from a moving pin into the photo cell is such a 'a system. A system of pin-hole lenses focus an image of the pin tops in the plane of patterned masks. The patterned masks (a grid havingalternating transparent and non-transparent patterns) are so arranged that :theV transmitted illuminationis a function of pin vposition with respect to the respective mask with a uniform light eld illuminating the pins. The light transmitted through the mask is focused on a photo cell whose output will have a varying component corresponding to pin wobble. If only one photo cell is used for all ten-pins, i.e., all ten pin irnagesrarefocused on a single photo cathode, the resulting system will produce a wobble-and-presence detector which will not indicate the presence or absence of any individual pins. Individuallpin wobble and presence isobtained by using a separate pin-hole lens and a. separate photo. cell to examine the image of each pin.

The additional versions of the systems all utilize an electro-magnetic phenomena for producing an electrical signal in response .to a wobble and presence. Variations in the electro-'magneticV or electrostatic fields unbalance electrical circuits to produce a modulated alternating current wave corresponding to wobble and a variable amplitude signal, or a change in the level of the signal toindicate pin presence.` VThese signals, in turn, are used in thesame manner as the signals from the photo-cathodes, for producing vthe desired eifects in the relay system used for initiating the operating cyclel of the pinspotter. Y

' It'V should be vstressed at this point that whatever the detecting system is, it must be capable ofpro'ducing two types of signals, one for indicating wobble, and the otherand ditferent type of signalf-for indicating presence. These two types of signals are rst produced in a common transducer and they are then separated from each other and directed to two separate control channels. The'wobble signals control the operation of the wobble signal channel, andthe presence signals control the operation of the presence signal channel. In the purely electrical detection systems, the transducer produces a modulated alternating current wave in response to wob-V ble, and a changerin the level, or amplitude, of the4 same alternating current wave in response to the absence of apin. In order to have a clearer understanding of the terms modulated wave and change in level, it may be helpful to say that the modulated wave signal is produced by using a pin wobble as a means for modulating4 a normally constant lamplitude alternatingY current produ'ced'by some suitable source, such as av crystalcontrolledV oscillator. The degree of modulation is a function of the amplitude of the wobble; the larger is the wobble, the larger is the modulation. The presence of a pin, on the other hand, produces a constant amplitude signal having a constant amplitude a when the pin is present, and a constant amplitude bf when the pin is absent with a beinggreater or smaller than 11. The wobble signal, produced by the labove, class of systems, shall be. called as the amplitudeA modulated signal, or the A.M. signal to correspond to the wellknown, and identical, amplitude modulation'used in radio, television and other forms of A M. communication systems, as differentiated fromrlF.M., or frequency modulation systems.V The Vpresence signal shallbe calledfthej level modulation signal (L M.) for lack of abetter term. ln

the above term, the word modulation means the changeV in the level of the signal which takes place when the pin is removed from its normal standing position, i.e., knocked down. -This change in level takes place at the moment the pin is knocked down. Y

. Y Y l channels into A.M. and LM. signals having an alternating current carrier for eliminating the use of direct current amplifiers.

This application is a division of my co-pending application, Serialv No. 650,634, tiled April 4, 1957, and now Patent No. 2,980,424.

It is therefore, an object of this invention to provide pin wobble and pinV presence detection systems.

Itis an additional object of this invention to provide purely electrical pin wobble and pin presence detection systems; r f

A further object of the invention isV to provide a novel pin fall detecting device wherein'pin fall is detected after each ball of a frame is rolled without the use of physical Vinto, amplitudelmodulated light signalV and the pin absence-and-presence is converted into a level-modulated light signal.

' It is a further object of the invention Vto provide a pin n.fall detecting Vand signalling mechanismY for use with a bowling pin for` use with a bowling alley whereinV there is generated a signal in the detecting system in response to the knocking down of a pinor pins normally standing on thepin spotting bed of a bowling alley, andrwherein the pin fall results are made known to a bowler.

It is an additional object of this invention to provide an improved *electrically controlled automatic bowling pin-setting machinehaving a control system Vcapable of responding to and controlling the time of operation of the machine when there is a wobbleof any pin, or, alterna tively, preventingrits operation when only pin #7 or pin #l0 is knocked down Iby the first ball when allV pins are present after ball #l or ball #2 are rolled without knocking over any pins, which are known as gutter balls.

it is a further object of this invention toV provide an improved control' system for Van automatic bowling pin setting machine, the control system having elf'ectrically"V controlled means responsive to the presence, absence and Y wobble of pins after an impact of aY ballV on the bowling pins, and having a relay system Vcapable, of timing the operation of the machine in response to the'pin wobble and pin presence signals. n Y

Yet another object of this invention is to provide a n pinspotter having a wobble-andfpresence detector pro- When the transducer is an optical transducer, two types-V Y frame and to indicate strikes and spares.

vided with a pinV presence system capable of furnishing a visual display indicating the pins left standing after the lirst or the second balls are rolled in the course of a The novel features which arebelieved^ to be characteristieof the invention, o oth, as to its organization and method of operation, together with further objects and advantages thereof, will be better' understood fromthe following description taken in connection withthe accompanyingdrawings in which several embodiments of the invention are illustrated as examples of the invention. It is to be expressly'understood, however, that thedrawings are forY the Vpurpose of illustration and deseription only, and are not intended as a definition of the elementsV of the invention. Referring Vto the drawings:

FIGURE l isa block diagram ofra wobble and presence j Y detection system; Y

FIGUREV 2 is a block diagram of anY optical wobble-V and-presence detection system;V

FIGURE 3 Vis a front elevational View of the Vcamera used in connection with the system illustrated in FIG; 2; f

FIGURE 4 is a plan view of the viewing mask for the camera illustrated in FIGS. 2 rand 3.

FIGURE 5 is a schematic diagram 'of the electronic channel of FIG. 2;

FIGURE 6 is a block diagram of an inductance pin wobble and pin presence detector system;

FIGURE 7 is the modified version of the inductance pin wobble and pin presence detector system disclosed in FIG. 6;

FIGURE 8 is a schematic diagram of the isolating detector used in the detection system disclosed in FIG. 7;

n FIGURE 9 is a block diagram of a detection system using a bridge circuit;

FIGURE 10 is partly a schematic diagram and partly a block .diagram of the detection system using an inductance bridge;

FIGURE 11 is a side view of a pin and flow coil used in conjunction with FIG. l0;

FIGURE 12 is partly a schematic diagram and partly a block diagram of the detection system using a capacitance bridge;

FIGURE 13 is a side view of a pin and capacitor mounted on the lioor used in conjunction with FIG. l2.

FIGURE 14 is a schematic diagram of the relay system operated by the detecting systems.

FIGURES l5 and 16 illustrate Ia suitable type of gutter ball detecting mechanism.

Basic components of the detection system Referring to FIG. 1, it discloses a simplified block diagram of a pin wobble and presence system for a single pin 2. When reflected light is used for detecting the wobble and presence of the pin, the pin nee-:ls no modifications of any kind. The light reflected by the pin produces the amplitude modulated light signal when the pin wobbles, and it produces the level modulated light signal when the pin is absent. These light signals are converted into the corresponding electrical signals by the detection system 3. The amplitude modulated signals (A.M.) are then separated from the level modulation presence signals in the detection system 3 and are impressed on a condenser 4 while the level modulation signals are impressed on a conductor 5. These two signals are then used to control the operation ofa pinsetter in the manner pointed out in the introductory part of the specication.

When the detection system 3 is all electrical, or electronic, system, a standard pin, without any additional modifications within the pin itself, may be used when a capacitive coupling between the base of the pin and a capacitor mounted in the alley licor is used for converting pin wobble and pin presence directly -into the A.M. and LM. electrical signals. When the capacitive effect is replaced with the inductive effect, it is preferable to mount a small coil at the base of the bowling pins for increasing the useful magnitude of wobble and presence signals. The bowling pins of the above type are described more in detail in the cov-pending U.S. application for patent of Milton Sanders having Serial Number 615,736, filed on October 11, 1956, now Patent No. 2,973,206, and entitled Bowling Pin.

The above detection systems are described more in detail below, beginning with the description of the opticoelectronic system.

Optico-electronic detection system The block diagram of this system is shown in FIG. 2, the transducer including a pin-hole camera It? is partly shown in FIGS. 3 and 4, and the schematic diagram of the detecting and signal-separating circuits is shown in FIG. 5. Accordingly, this system will be described in connection with FIGS. 2 through 5. The transducer, per se, which transforms mechanical movement of the pins, such as wobble and presence-absence, includes a source of light 30, pins I2, a pin-hole camera Iii, and a mask 24 mounted within the camera. This optical transducer converts the pin wobble into an amplitude-modulated light signal and pin presence into a level modulated light signal. These light signals are focused on the photo-cathode 52 of a photo-cathode multiplier 50, FIG. 5, where the light signals are converted into electrical signals and the electrical signals are then used for controlling the operation of the pinspotter machine. FIGS. l through 5 illustrate only one optico-electrical detection channel for one pin; the overall system includes ten identical individual channels of the above type, one channel for each pin. Each channel furnishes information concerning the status of its pin in terms of wobble and presence and these signals are used for controlling the operation of the pinspotter. Only one wobble-and-pres'ence channel is illustrated for simplifying the description and drawings.`

Referring to FIGURE 2, it illustrates Ithe relative position of camera It) with respect to the alley floor l1 and pins I2. The most advantageous location for camera 11i is on an alley mask 13 directly 4behind the pinfall signal means 14. Camera 10 for pin #l is in a vertical plane passing through `the central, longitudinal axis of the alley, and the remaining cameras are positioned to the left and right of this camera. The cameras lfor thelback row pins (7 through 10) are placed above the first row of cameras. Such positioning of the cameras produces reasonably uniform in size images of the pins, in the respective cameras, making the signals from the various pins more nearly uniform. The cameras, thus mounted will not be subjected to vibrations as they would be if mounted on the machine. An additional advantage of such mounting is that `the camera is very unlikely to be hit by dying pins in this location.

Referring now to FIG. 3, it illustrates the front view of the camera. It is mounted in a box 1S having two identical front plates I6 and i7. Plate 16 is provided with a single pin-hole I3, while plate 117 is provided with three pin-holes 1.9 through 21. The pin-hole plates 16 and 17 constitute lthe front ends, or faces, of two independent cameras, one camera, with plate 16 and pin-hole I8 being used to focus the image of the upper portion (the upper rounded end) of some particular pin on a mask 24, FIG. 4, while plate 17 and pin-holes I9, 20 and 21 are used for focusing the general background alley illumination' on the photocathode used for compensating the detector against any liuctuations in this illumination. (not shown) which supports the mask approximately three quarters of an inch 'behind the pin-hole plate I6. Only one mask is used in one of the cameras, such as camera 16 which is used for detecting pin wobble and pin presence. The illumination compensating camera 17 does not require the use of any mask. Mask, or grid, 24 is made of transparent base material, such as glass or cellulose acetate film, with a non-transparent grid pattern 2S superimposed on the transparent base. The preferred version of the grid pattern, which was found to produce maximum amplitude variations, consists of a saw-tooth wave 26, projecting beyond the straight strips. It has been found experimentally that such pattern produces the most uniform amplitude signal from all the pins located in various positions, and

no pin in the eld of view of the camera and the grid can move in any manner without a change in the intensity'of the light transmitted through the mask. Thus there is no problem of orientation of the mask with respect to the pin images. The widths of the opaque strips, clear strips and sawtooth edge are equal to each other. The sawtooth angle -is 45 The function of the sawtooth ,edge on the mask is to increase the signal produced by the foreshortening of the pin image as a pin wobbles back and forth toi-ward and away from the camera. Versions of this mask with various scale factors are not critical as long as the mask is not so coarse as to per` mit a pin .to wobble without part of its image moving` out from behind an opaque strip into the sawtooth, or

Mask 24 is mountedon a metallic bracketV 7,. clear area, and not so fine as to lose signal strength. The' marks are also scaled so that the width of the opaque strips at their narrowest points is kmade equal to the width `of the .incident image of the pin neck. In the -illustrated'version of the mask, the indicated dimensions a, b and c areequal to each other. It is to be understood .that this invention is not restricted to the above-mentioned configuration of the mask, and other patterns can be used successfully so long as the above basic considerations are kept in mind.

' The pinhole camera 10, illustrated in'FlG.' 2,V uses a pinhole in each came-ra for detecting the pin wobble and presence. A pinhole lens, sufficiently small to resolve the head of a bowling pin (in one exmple the pin holes were .03 inch in diameter), admits suificient amount of light to permit operation of the detector with a reasonably simple and inexpensive photomultiplier circuitry; A pinhole lens is simply a hole, of a proper size and placement, drilled in a sheet of opaque material. The pinhole lens, in addition to its obvious advantage of low cost, also has a wide angle and provides an'image of of an infinite depth of focus; thus the pinhole lens can be focused on the king pin or on the rear pin, and its iield of view may be controlled by varying the distance between the pin hole and the photo-cathode. Three pinholes are used in camera 17 illustrated in FIG. 3 in order to obtain a `better integration of the overall background illumination.

' The sensitivity of the photomultiplier tube. .is not uniform lover the cathode surface, but is highest in the central region and drops rapidly toward the edges of the cathode. This is probably due to a higher multiplication being obtained with electrons leaving the central portion of the cathode than from those leaving the cathode load is connected to the source, i-t is apt to produce either transients or variations in the magnitude of such voltage, or both, which are apt to influence proper operation of the detectors. VIn order Ito cancel lthe effect of such tran- Sients and fluctuations in the intensity of illumination, the detector is provided with the compensating viewing head, or camera, 17 illustrated in FIG. 3, which isV identical to the viewing, or camera, 'i6 used for producing the wobble signal except that it has three pinholes 1?- 21 andno mask. A photomultiplier is also mounted in the back of the viewing head 17 `to convert the light passing through the pinholes into an electrical signal clarity, relatively independent of object distance because Y which compensates for any voltage fluctuations. Accordingly, head 17 produces a signal which is proportional to the intensity of illumination, but'it is nonresponsive to the wobble, rolling ,or spinning of the pins. In View of the absence of mask 24 in head l7,.sorne difference in the overall intensity of illuminationl will generallyY occur when some of the pins are spinning or rolling and such signal, as a rule, will also be converted into an electrical signal. These signalshave a sutliciently low amplitude and, therefore, do not affect the operation of the pin setting machine.

., The outputs of the twophotomultipliers are connectedV to adiierence circuit 32., the output of which produces.

These, signals awobble signalV and a presence signal. are used for timing theV operationy of the pinsetter. The effect of light intensity fluctuations, therefore, is substantially cancelledout because bothcameras are equally affected by the random fluctuations in the intensity due fto voltage fluctuations. The lphotomultiplier.load retwo viewers, with all pins standing. Complete compensation of light changes occurs only whenall pins are standing'. However, the useful signal has a suliiciently large amplitude for practical purposes.

In order to minimize the erect of the line voltage on the entire detector still further, it is desirable to use a regulated voltage supply which uses voltage regulator gas filled tubes. Such regulated voltage supplies are well known in 'the art and,4V therefore, need no further description. f

The Voutput ofthe diiierence'circuit 32 produces two signals: one signal is the amplitude modulated signal corresponding to the pin wobble, and the second signal is thelev-el modulated signal Ycorresponding Vto pin presence and absence. These are the previously mentioned A M. and L M. signals.V The two signals are both impressed on a presence amplifier 33 where the wobble signal is filtered out so' that only the LM. presence signal has any effect on a pin presencerelay 35. The functions performed by thisY relay-will be described later in connection'withthe description of the relay system shown in FIG-i4. g i

The A M. wobble and L M. presence signals are also impressed Vonthe wobble signal channel which begins with a low pass filter 34, where higher frequencyzcornponente than those encountered in pin wobble are effectively discriminated against by this filter. This filter, together with other filtering elements, such as the low pass lter in the photomultiplier circuit mounted in carnera 3l, limit the bandpass characteristics of the circuit so that the only spurious signals which can affect the pin wobble detector, are ythose with frequency components similar-to those produced by pin motion. The effects of long term changes in illumination for example, are filtered out by coupling capacitors in the wobble signal channel, while' very rapid transients are removed by the low pass filters. T he output of the low pass filter 34 is impressed on an amplifier 36, and then on a rectifier and limiter circuit 38 the output of which is impressed on a sharp cutoff pentode amplifier 46. The output of pentode 4t) energizes a relay ft2, which has armatures 43 and 44. Armature 43 is used for controlling the operation of the pentode, while armature'f-E-d is used for timing the operation of the pinspotter in the manner which will 'be described later in connection with the description of the relay system shown in PEG. 14. Relay 42 will be called the wobble relay because iti-becomes energized in response to pin wobble. As will be pointed out later, the normally closed contacts V42a of ten wobble relays are connected in series with the main relay of the pinspotter and, therefore, the pinspotter relay is energized immediately if there is no wobble or its energization is delayed as long as any of the ten pins continue to wobble. rl`he very moment wobble ceases, relay 42 becomes de-energized, the circuit of theV main pinspotter relay becomes closed, and the pinspotter is put into operation. Accordingly, the operation of the pinspotter is controlled by the wobble relays 42. There is an instant starting when there is no wobble, the length ofthe delay being controlled by the wobbling'pin. Y Y i Referring to'FIG. 5, which is the schematic diagram of FG. 2 lup to and including relay 42, the photo-V multiplier 56 is the masked photo-multiplier, while photomultiplier 5l is the compensating photoem'ultiplier. The light sensitive vphoto-.cathode 52 receives lthe wobble and the presence signal and the average illumination signah' grounded through a grounded conductor V54. The anodes 65 and 6u are connected to a `positive source of potential 121 through a conductor 76, fixed Vanode resistors 67V and 68 and variable resistors 69 and 7i?, respectively. The cathodes 52 and 53 yare connected to the negative terminal of a high source of potential 741-, while the positive terminal of this source is grounded. Condensers 7l and 72 are also connected to the respective anodes on one side and to ground on the other side. Condensers 7l and 72 act as low pass filters and serve reduce the 120 cycle per second signal which is the modulation signal appearing on the anode due to the double line frequency ripple produced by the alley illumination. These condensers also reduce the anode modulation, which in turn reduces the linear dynamic range required of the dicrence circuit operated by the photo-multipliers. The variable resistors 69 and 7@ are adjusted, so as to make the two anodes 65' and 66 `at the same potential with respect to ground when the pinholes in two cameras are open and the pins are standing on the alley floor.

Since the corresponding dynodes of both photo-multipliers are connected together to the taps on the chain of the common resistors 54 through 62, some crosstall; signal is produced because of the use of the common dynode resistors; this crosstalk signal is largely cancelled out in the difference circuit and does not signilicantly affect the overall operation of the pin wobble detector. A further reduction in the crosstalk can be obtained by providing an independent chain of resistors for the photo-multiplier Sl.

The output of the photo-multiplier l? is connected through a conductor 73 to the grid of a triode 75', while the output of photo-multiplier 5l is connected through a conductor S5 to grid $4 or" a triode 77. Triodos 77 F5 are conventional cathode follower impedance multiplier stages, and are identified as such by the fact that one terminal of the grid resistance Si) is connected to a tap 82 on tre cathode load resistance 7S-S3 through a biasing battery 37. Resistance 78 is a high resistance as compared to resistance S3. The direct current impedance seen from grid 3:3 to ground is several times the value of the grid resistance el?. rl`he same is also true of grid S6 and its circuit. More-over, the impedance multiplying circuit has a high input impedance and, therefore, does not reduce greatly the photo-multiplier signals by shunting them to ground. The cathode followers 77 and 75 lhave low output impedance and, therefore, long leads 87 and SS can be run from the cathode followers to the remainder of the circuit which is mounted outside of the camera box l5'. rhesc leads are connected to the difference circuit 32 which includes a double triode 9d having its `cathode connected to a common cathode resistor 4l. Grid 92 is connected through conductor resistances 93 and 95 and a biasing battery 96 `to the cathode of triode 77, while grid 9i is coupled to the cathode of triode 75 through conductor S7, grid resistor 98 and a biasing battery 97. Grid 92, therefore, receives only ythe signal which represents the intensity of illumination and variations in the intensity of illumination due to the voltage fluctuations, while grid 91 reeives the signal proportional to the intensity of illumination, and the variations in the illumination, the wobble signal, and the presence signal. The difference circuit, as its name implies, has an output proportional to the difference of the signals from the two impedance multipliers. The difference circuit output is thus proportional to the difference in the two signals produced at the two photo-multiplier anodes. Viren the intensity of illumination fluctuaties, corresponding to a line voltage fluctuation, approximately equal signals are produced at the two photo-multiplier anodes, and the output of the difference circuit is very small. ever, the signal produced at the anode 65 of the masked photo-multiplier Sti is very much larger than that produced at the compensating photo-multiplier anode. lt is also of different algebraic sign in a random fashion. A detailed description of the difference circuit is not necessary because the circuit of this type is known in the When the pin moves, how- CII lil

art. Suflice it to say that the difference signal, corresponding to the wobble or presence signals, appears across a plate resistor lill. The positive signals impressed on grid 9i produce a positive signal on conductor 39, condenser lili? and the two cathodes. Plate @3A becomes more positive in response to the above because of the reduction in the space current. Therefore, a positive signal is impressed on conductor 39 and condenser lill?. When grid 92; becomes positive, plate 93A becomes more negative because of the increase in space current and conductor 39 and condenser lill) receive a negative signal thus subtracting itself from the positive signal produced by grid Qi.

The wobble AM. signal and the presence LM. signal both appear 0n conductor 39 and are impressed on condenser ll, which couples the wobble channel to the I difference circuit, and on the control grid ll of la pentode 15d. The wobble channel, through its coupling condenser llll and a low pass filter condenser lll, elimihates the presence signal and transmits the A.M. wobble signal for energizing the wobble relay d2. The presence channel, including pentode lSll, shunts to ground the AM. wobble signal through a capacitor 152, but the variable level signal, which may be regarded as a direct current signal, is impressed on grid ll making pentode l5@ more conducting. This increase in plate current energizes the presence relay 35. RelaySS is shunted-by a capacitor E53 which improves the operation of relay 35 by decreasing the difference between the currents which are necessary to energize and cle-energize relay 3S.

Reverting once more to the wobble channel, the wobble signal is impressed on the 'control grid of a pentode amplifier 99 through capacitor llli'l and resistors lll3 and ill-l. The grid resistor lll-4 is shunted by a capacitor ltlS the value of which is made so yas to actas a low pass filter to ground. ln one example, resistor M34 had a value of l megohm, while condenser 1%' has a value of 2 microfarads. Higher frequency components than those encountered in pin wobble are effectively discriminated against by this filter. This filter and the other filtered elements, such as condensers 7l and 72, limit the bandpass of the circuit :so that the only spurious signals which can affect the pin wobble detector circuit are those with frequency components similar to those produced by the pin motion. The effects of long-term changes in illumination and the presence signals for example, are filtered out by coupling capacitors in the wobble signal channel while very rapid transients are removed by the low pass filters including condensers 7l, '72 and lllS.

The pentode 99 circuit, which is connected and operates as a Class A ampliiier, .includes a fixed cathode resistor lilo in series with a gain control potentiometer ll7. The output of amplifier 99 is connected through a capacitor lll@ to a detector and a limiter circuit including a twin diode M9 and lib. The detector 169 is connected across a resistor lll and in series with a signal storage capacitor 112 so that only positive signals impressed on plate ll make diode lll conductive and, at the same time, charge up condenser 112 with the upper plate of the condenser, which is connected to the contro-l gridflA of a pentode amplifier 115, becoming more positive when diode lll becomes conductive'.V Therefore, the wobble signals mal-:e pentode MS conductive. The second diode llt) acts as a limiter of the positive signal impressed on grid 114 because it is connected across condenser M2 through resistors llo and 117 and a conductor lll. The two resistors llo and 117 act as potential divider resistors connected between grounded conductor 12b and a source of potential 121. When the voltage impressed on the plate of diode lill becomes higher than the voltage impressed on its cathode by source 121, diode ll@ becomes conductive and thus limits the potential that may appear across condenser ll?, and, as a consequence, also limits the positive signal impressed on grid H4. Because of the limiter lllielll, the time delay between cessation of a very large signal andresumption of pinspotter operation is no longer than Yfor smaller signals.

The output of limiter lill 'is impressed on grid 114 of pentode 115 which has a circuit to produce sharp cut-oil. Cathoder139 of this pentode is connected to ground through resistors 134 and 135 and a tap 117 between these resistors is connected over a conductor 136 to the 'normally closed contacts 42h of relay d2. The winding of relay 42 is connected in series with the plate circuit of pentode 115. The left contact 42h is connected directly to cathode 139 over a conductor 137 and armature 42d is on contacts 421) when relay 42 is not energized and it opens contacts 42]) when relay d2 is energized. Therefore, with no wobble signal, the cathode resistor 135 lis shunted byarmature 42h' resting on contacts 42h; shuntingof resistor 135 reduces the positive cathode bias on cathode 139 as long as relay 4?; is not energized,

When relay 42 becomes energized, the short circuit 'Y across resistor 135 is removed and it becomes connected on cathode 139 is increased upon energization of Yrelay d?.

which decreases the magnitude of the grid signal required for cle-energizing -relay42 and also decreases the diflerence in grid voltage between the level at which relay 42 is energized and that at which it is cle-energized. The relay winding 42 is shunted by a capacitor 123 for eliminating contact chatter. Condenser 23 is also used for holding relay 42 energized if there is aV momentary` decrease inthe wobble signals below a predetermined level by discharging condenser 122 through winding Mil. Conductor 66 connects relay d2 to the positive terminal of source 121. Conductor 65 is also connected to conductor 13d through a resistor 131 for obtaining proper bias of pentode 115. A wobble signal, impressed on grid 144 is a positive signal and, therefore, it causes an increase in the space current, which causes a current increase through winding l2 and if this increase in current is sufficiently large, relay 42 will become energized. Normally tube 115 is non-conductive since grid-i141; is at ground potential and cathode 133 is at some positive potential determined by the values ofthe resistors 334 and l which are connected across the power supply 121i. Therefore, grid 114 is at a negative potential with respect to cathode 133.

The wobble relay 42 controls the time of closing of i the pinspotter main relay 3%2 since contacts 42a and conductors S' and N6 are connected in series'with the main pinspotter relay, as will be described later in connection with the description of FG. 14.

Impedance pin wobble and pin presence detector The impedance type pin wobble detector belongs to the class of pin wobble detectors which requires the Yuse of sensors, or detectors, in the alley floor. An impedance pin wobble and pin presence detector involves the measurement of thechange in the impedance of a circuit.

' Looking into the sensors in the alley floor, such change in the impedance may be produced by'using capacitors orV inductance coils as sensing devices. The sensing system using inductance coils is more sensitive than that Yusing the capacitors and will be described irst and it will be followed with the description of the capacitive system. Y

VInthe inductance system, the pin wobble and pin presence signals are produced by a continuous measurethickness which would protect the coils fromV ordinaryV wear and tear. The insulating material suitable for this purpose is the Permabase plastics material described in Vacts as an indication of pin wobble.

12 the U.S. Patents 2,739,814 and 2,680,023. A iloor coil may consist of a suitable-number of turns of'wire with a capacitorV connected across this coil to tune the circuit to the operating frequency with the pin removed from the alley floor. Although the frequency range of such system is not critical, the ultra hiUh frequency (UHF) and the high frequency range is less desirable because the losses in the surrounding medium at these higher frequencies are larger than at the lower frequencies. On the other hand the audio frequencies would require large coils which are not suitable from the practical point of View. Accordingly, the range of frequencies'which is most suitable for the systems of the above type is between 100 kilocycles'and 2 megacycles.

When the pin is placed on the iloor coil, connected to a source of carrier frequency, and wobbled, a modulated carrier signal is produced. The modulated carrier'signal Moreover, an increase in the amplitude of the carrier (level modulation, mentioned previously) is produced when the pin is removed or knocked over because of the decrease in the losses produced in theoor coil by the pin coil. Accord-` ingly, the amplitude modulated signal and change in theV level of the carrier signal, may be used for obtaining an indication of pin wobble and pin presence, respectively. The wobble signal is obtained by detecting its amplitude modulation. produce the carrier level output signal, which is the direct current output, for indicating the presence of any individual pin. A block diagram of such system is illustrated in FlG. 7. The circuits used in the'inductance pin wobble and pin presence detector are known in the art and, therefore, no schematic diagrams of the circuits is necessary. However, suitable specic circuits will be mentioned in the course of the description of the block diagram, to identify the types of circuits which are capable of performing the intended functions in the optimum manner.

Referring to FIG. 6, a coil ddd-or an electronically equivalent element, is installed in the base of a standard pin. Maximum useful signal is obtained if the pin coil is tuned to the frequency of the applied voltage. The output l signal may be increased, for example, ten times since it Y dell connected across the coil to theV frequency of the oscillator used for producing the carrier frequency. Since each inductance coil has its own resonance frequency, it is also possible to use only a coil 6de without any use of condenser ll so long as the coil is made resonant at'the carrier frequency. Bowling pins of this type, provided with a single coil, or a plurality of turns and the electronically equivalent elements, are disclosed more fully in the previously mentioned Patent No. 2,973,206 which is made a part of this disclosure. The floor coil 692 and the condenser otl are tuned to the same carrier frequency and the tuned circuit 602-693 is connected to a cathode follower 664 through a resistor 695 and a condenser 606.

' With the impedance looking into Vthe tuned circuit from the cathode follower 694 being made equal to the output impedance ofthe cathodeY follower, a lifty percent change in the output voltage may be obtained in the output sig-v nal appearing ona conductor 607 when the pin coil is removed, i.e., when the pin is knocked over. It should be stated here that ten identical channels, one channel for each pin, are required with theV system disclosed in FIG. 6, Vonly two channels being illustrated infthe ligure.,` A single oscillator V698, such as a tuned grid oscillator, is used for impressing the carrier frequency on the ten tuned Y circuits. A lt is preferable to have a crystal controlled os- Oscillator 6tlg Vis isolated from the tuned circuitsV byrinter- Y cillator to avoid frequencyV drifts and the loss in the sensitivity of the circuits due to such frequency drifts.

posing an ampliiier'oiliand a buffer amplifier, or a cath- The same detector canalso be used to ode follower, 610. The buffer amplifier 610 is connected to ten cathode followers 664 over a conductor '66@ `with each cathode follower-ddd being connected to the respective floor coils 692. Oscillator 698 thus furnishes the carrier frequency to the ten tuned circuits. The output of the tuned circuits is connected over conductorii? to a detector 611. The direct current output of detector 611 is connected over a conductor 612 to a direct current presence amplifier 613. The signal impressed on amplifier 613 represents the average level of the signal appearing in the output of detector-611. This average level is constant when there is no wobble and its level is modulated when there is a wobble. It increases greatly when the -pin is absent.

The direct current presence signal (the `previously mentioned level modulation signal) is impressed on a presence amplifier 613 through a metallic, direct current path by connecting the plate of detector 611 to the grid of the presence amplifier 613, the plate resistor of the detector also acting in such case as a grid resistor for the grid of the presence amplier 6H. Amplifier 13 corresponds to the amplifier 33 in FIG. 2 and -pentode 15@ in FIG. and performs the same function as the above elements in FIGS. 2 and 5. The output of the presence amplifier 613 is connected to the presence relay 35 corresponding to the identically numbered relay in FIGS. 2 and 5. The operation and the control functions performed by relay 35 will be described later in connection with the description of FIG. 14.

The output of detector 611 is impressed on a wobble amplifier 621 which'corresponds to the wobble amplifier 99 in FIG. 5 and amplifier 36in FIG. 2. A low pass filter 34 may also be included inthe wobble channel. In general, the wobble channel in this detection system is identical to the wobble channel 34, 36, 38, 40 and 42 of FIG. 2, and the same channel shown in schematic form in FIG. 5. Condenser 622 in FIG. 6, therefore, corresponds to condenser 16@ in FIG. 5. The wobble relay 42 in FIG. 5, therefore, performs the same function as the wobble relay 42 inthe prior figures.

Gne of the advantages of the system disclosed in FIG. 6 is that it uses only one oscillator 608 for producing a carrier frequency for all ten channels. At the same time, the use of one oscillator requires a careful tuning of the floor and pin coils 692 and 600 and capacitors 6133 and 661. The system disclosed in FIG. 6 performs well once the tuned circuits in the pin and in the door are properly adjusted. One .additional factor which one should take into consideration in connection with FIG. 6 is that the length of the cable between the tuned circuit 692-603 and the cathode follower 604 causes the effective Q, or the ligure of merit, of the floor coil to be lower than the measured Q of coil-602.

he operating charactristics of the system disclosed in FIG.Y6 may be improved by providing ten separate oscillators with the iioor coils themselves being the frequency determining elements by making these coils as an integral part of the oscillator with the oscillator and detector mounted in the center of the floor coil form. In this manner the length of the cable between the oscillatordetector and the coil is reduced to zero. Moreover, such construction is capable of increasing the signal level enough to make the precise tuning of the pin coils unnecessary. v

The system ofthe above type is illustrated in FIGS. 7 and 8. FIG. 7 illustrates a block diagram of the circuit, while FIG. v8 illustrates the schematic diagram of a suitable oscillating detector circuit which can be used for producing the individual carrier frequency signal and detection of this signal in each individual channel. The performance of the system disclosed in FIG. 7 is superior -Vto the performance of the system disclosed in FIG. 6,

but it requires the placement of the oscillator detector circuit in the center of the oor coil formand requires ten oscillatoretectors. This disadvantage, however, is

vld

more than compensated by the superior performance `of the system.

kReferring to'FIG. 7, the pin coil-capacitor combination 7% is coupled, as before, to the licor coil-capacitor combination 701 and the latter is connected to the oscillating detector circuit 702. The output of the oscillating detector isimpressed onfa conductor 703 to indicate the presence of the particular pin while the wobble signal appears on conductors 704 and 705 which are connected to each other through a .capacitor 766. Identical elements are used in each channel for each pin and, therefore, there are ten channels altogether. A grounded resistor' 767 is used as a grid leak and also as an output impedance vofthe oscillating detectorcircuit illustrated in schematic form in FIG. 8. Conductors 703 are connected to the individual presence amplifiers, such as amplifier 613m FIG. 6, and :amplifier 15d in FIG. 5, and

the wobble signal, appearing on conductor 765, is impressed on the wobble signal channel videntical to that shown in FIGS. 2 and 5. Conductor 765 and capacitor 706, therefore, correspond toy conductor d5 and capacitor 19t) in FIG. 5. The relay system operated vby the detector circuits of FIG. 7 is identical to the `relay system of the prior figures and that disclosed in FIG. 14.

FIG. 8 discloses the circuit of the oscillating detector which can be used in block 702 of FIG. 7. The oscillator is the Hartley oscillator. The pin coil 820 (with or without a condenser 821) iscoupled as closely as practicable from the point of view of wear Iand tear to the 'floor coil 822 which has a tap 823 connected to the cathode of triode 824. Coil 822 is shunted by a condenser 825. The tuned circuit 822-825 is coupled to the grid by `a capacitor 26. The grid` is also connected to ground through a resistor 827. The presence and the wobble signals are impressed over :a conductor 328 on the presence channel similar to that disclosed previously, and the wobble signals are impressed through capacitor 106 on conductor 45 which correspond to the identically numbered elements in the prior figures. When the pin coil is in 'the proximity of the iioor coil 822, the overall Q of the tuned circuit is not as high as when coil 320 is absent. Accordingly, with the pin standing, the amplitude of the oscillator is not as high as with the pin absent and, therefore, the amplitude of the alternating signal appearing across resistor 327 is not as high with the pin standing as it is with the pin absent. When the pin is absent, the detector oscillator develops a large negative grid voltage 'appearing kacross resistor 827 and this signal is impressed on the outgoing presence channel. The wobble channel iilters out vsuch signals, through the coupling condensers and the low pass filters described previously and, therefore, t'he'operation ofthe wobble-amplifier 99, FIG. 5, is not affected by the presence signals.

The circuits disclosed in FIGS. 7 and 8 are thus capable of detecting the wobble and presence of the pins and, furnish two distinct signals, the amplitude modulation wobble signal and the level modulation presence signal, which can be separated in the electronic channels and then directed to the relay circuits of the type illustrated in FIG. 14 for controlling the operation of the pinspotter in the manner which will be described in connection with FIG. 14.

FIGURES 9 through 13 disclose additional versions of the inductance and capacitance pin wobble and pin presence detectors which use a Wheatstone bridge for detecting the wobble and presence signals produced by the individual pins. FIG. 9 is a block diagram for such systems. The base of pin 991 is provided with a coil ora coil-condenser combination if the Wheatstone bridge 992- 903 is Ian inductance bridge. If the bridge is a capacitive' bridge, the pin itself acts as a capacitive element and, therefore, conventional pins may be used without the insertion of any additional elements 'in the base of the pin. The bridge circuit is connected either to a local oscillator or an oscillating detector of the type shown in FIG. 8.

` numbered conductors in prior systems.

i portion of pin 1003.

nected to a carrier source 1905 whose frequency may be in the rangejof 50,000 cycles per second and 2 meg-awa part of this disclosure. l V Since this invention uses severaly phases of the functional .Y cycle of the machine disclosed in the U.S. Patent 2,559,-

Yis

' The output of the bridge is connected to an ampliiier 2,559,274 and the remaining'elements ofthe overall relay inductance coils 16130 in the alley'lloor and an inductive Y ring 1tll2 or a coil or a permeable insert at the bottom In all cases the bridges are conc'ycles per secondV as describedpreviously.

FGS. 12 and 13 .illustrate a capacitive bridge detector, or transducer; in such transducer, metallic plates 12th) and 1201 are mounted in the licor of the alley in the manner illustrated in FIGS. 12 and 13 to form individual capacitors. In such case a pinlStlil, may be a conventional pin with or without yany metallic inserts in its bottom portion; the bottom portion can also be made of the l plastic composition known as Permabase mentioned previously." In either case, wobble or absence of the pin Vproduces an unbalance in the inductance or capacity bridges and this Vsignal or signals are used for controlling the pin-spotter in the manner described below. 'Y -In summarizing the systems using an impedance bridge,

the inductive systems require that a mass ofrpermeable 'materiaL 'such as an Velectrically conducting ring or a coil, be placed in the pin bottom@ In either case, mo-

tion of the pin changes the inductance ofthecoil placed .in the licor, under the pin, and this change' of inductance can be measured by .using an alternating current bridge whose output is amplined and used yto control the pil.- spotter cycle. Such transducer furnishes the presence and the wobble signals and coil inductance is measured continuously. The absence of a pin causes a reduction in the amplitude of the signal, while a wobbling pin produces a modulated signal. The two types of signals are separated in the manner described previously in the two channels.

The knocked-over pins will produce only avery small inductance change when rolling or spinning on the oor and, therefore, the systems of this type can ybe made to interrupt the pinspotter cycle when pins are wobbling without responding to the rolling or spinning pins.

The same is also true Vof the system using a capacitance bridge illustrated in FIG. 12.

Relay system for controlling the operation of pz'nscing l Y machine Patent 2,559,274 dated July 3, 1951 which is made a part There are now in use throughout the of this disclosure. United States later versions of the machine distributed by the American Machine 8c` Foundry Company the as- Y signee of the above patent and of this application.V The 'teachings ofvthis invention are also applicable Vto the ma- Vchines now in actual use which, for example, are described, in part, in Product Engineering June, 1954 issue, and Roger E. Dumasapplication for patent'SN.

226,359, tiled May`15, 1951, and now Patent No. 2,821,-

system are omitted altogether. However, the functioning of the entire relay system'will be apparent to those skilled in the art from the description of the modications'in the relay system appearing in Patent 2,559,274. In order to faciliate the understanding of the description of the relay systen and its relationship to FlG. 4 in Patent 2,559,274, those elements ofthe relay system of FIG, 4 of the patent, which are also shown in FIG. 14, bear the same identitying numerals as those used in the patent and such elements, for a more ready identification are put in quotation marks` For example, the pit switch 369 indicates that it is identical to the identically numbered'switch 39! in FIG. 4 of the patent.

'Wobble syslm The operation of the wobble detecting systems has been described previously'. g that the wobble relay contacts 42a normally are closed ItY also has been stated previously and become 'open only Ywhen relays 42 receive wobble signals. Accordingly, these relays can control the starting time of the entire machine by connecting these ten wobblerelays in series with the main relay 3627 Iand the pit switch Still in the manner indicated in FIG. 14. A source of potential 146; is connected in series with conductors 391, 30161, wobble relay contacts 42a and the `relays 42. Accordingly, the entirecycle of the pinsetter is now controlled not only by the closing of the pit switch 36th as disclosed in the above patent, butY also by the ten wobble relays 42144210, any one of which is capable of delaying the operation'of themachine until the wobble ceases, whereupon, the affected relays 42 become cle-energized, contactsV 42d become closed, and the oper-ationof the machine/takes place the very m'o-rnent'the .wobble ceases. Relay 362, therefore, is a fast-acting relay as differentiated from the delayed closing rel-ay 302 in the above patent. Once the relays 42 are all closed, when all wobble ceases, the machine is allowed to operate without any, other delay. When there is no wobble, the machine Vis permitted to operate immediately after ball strikes pit switch Still and the fast-acting relay 302 is energized. The operation of the machine, from 'then on, is identical to that disclosed in the above patent with the modifications which are pointed out below, and which are caused by the prevention otits normal operation. Y

` (1) When the iirst ball is a gutter ball; when the first 395, Vthe latter being also incorporated by reference as 274, it is unnecessaryto disclose here the overall .structure of the machine; such structurels fully disclosed inthe v Y above patent and a more 'recent U.S. Patent 2,773,689

granted Decemberfl l, 1956. The same is also true of the relay system disclosed in FIG. 4 of the Patent 2,559,274,

14 in this application illustrates only the modifications ball as well as the second ball are both gutter balls;

,'(2) When only pinV #7 or pin #10 is knocked down by i the first ball, and all other pins'are standing. From ,the above ldescriptionY of the wobble relay circuit,

it-follows that the initial starting of the machineris now controlled Vbythepit switch 39,0 as. well as ten wobble relays 42. There Yis, anpinstantaneous starting of the machine when there is no wobble after the iirs-t or the sec-V ond ball or anyA other ball, and a variable delay starting if there is a wobble, in which cases the machine is started immediately ter vthe` wobble ceases.'`

` Pin presence system The pin presence, signal isimpressed one directeur- Y rent amplifier 33, FIG, 2, .and then a pin presence relay bowling pin standing on the alley door, is that illustrated in FIGS. 2, 5, 6, and 14. Contacts 35a are open and contacts 35b and 35C are normally closed with the eX- Ception of contacts 3511 on relays 357 and 35m, which are normally open and are connected in parallel by means of conductor 1461 and 1492. All the remaining contacts 3511 are normally closed with the pins standing and are connected in series with each other and conductors 1461 and 14112. Conductor 1463 is grounded and conductor 1404 is connected to cam-operated contacts 35d and 35e which are closed and opened by a cam 35 having the contact-closing portion 1495 extending over approximately 160-l70 of the cam 35i. Cam 35]L is keyed to a shaft 255 corresponding to the similarly numbered shaft in the patent. lt is the electrical control cam shaft on which all electrical control cams are mounted, as described in col. 8, lines 62-75 and col. 9, lines 1 and 2 of Patent 2,559,274. As stated in the above description, the control cam shaft 255 makes only one revolution for every two revolutions of the main cam shaft 2S and is driven by shaft 28. The control cam shaft 255 makes one revolution for every two balls, and one half of a revolution for the rst ball and the remaining one half revolution for the second ball. Contacts 35b of the presence relays 55 are that set of contacts which are used for eliminating the operation of the pinsetting machine when only pin #7 or pin #'10 is knocked out by the rst ball and all other pins remain standing. As mentioned previously, it is unnecessary to lower the table and reset the pins under the above conditions since the remaining pins are standing in proper manner and positions and, therefore, are immediately ready for rolling the second ball. The series circuit which controls the operation of the machine under the above conditions is grounded source 14511, conductor 14%, winding 14% of the relay having two sets of contacts 1st-@6a and 1411619, conductor 14117, contacts 55e and 35a', which are closed during the rst ball play, conductor 14114, closed contacts 35!) and grounded conductor 141115. Contacts 35b remain closed as long as pins 1 through 6, 8 and 9 are standing and contacts 3557 or 35h10 become immediately closed if either pin #7 or pin #'10 is knocked down by the rst ball. Closing of contacts 35b7 or 35h10 completes the circuit and this energizes relay 1405. When relay 14d-5 becomes energized, contacts idtlda open which prevents energization of the clutch relays 361i and 14518 which prevents the lowering of the table. Relay 360 corresponds to the similarly numbered relay in Patent 2,559,274 and, as described in the above patent, it is used for actuating clutch 1i-4. This prevents engagement of clutch l 4, and thereby prevents the setting of new pins but allows the machine to operate and return the ball to the player. The functioning of clutch K-d per se in the machine disclosed here is identical to the functioning of clutch l-4 in the patent. The diiference resides in the interposition of relay 1496 which prevents the actuation of relay 361B when only pin #7 or pin #l0 is knocked out on the first ball and when the first ball is a gutter ball and the second ball is also a gutter ball. The circuits of all clutch relays, such as l-1, l-2, and K-S, are identical to the circuits in the patent and, therefore, need no description. The circuit of clutch Ii-4 differs only in one respect; i.e., an additional control relay 1496 has been connected in series with the following circuit: a grounded source 1410, conductors M11, 1412, contacts 561e of relay 361, conductor 1413, contacts 1496s, conductor 1414- and grounded winding 369. With the exception of relay 1466 and contacts 145166:, this circuit is identical to that in the patent and normally performs the same function as long as contacts Miln remain closed. The circuitry and the functions performed by relay 361 remain the same as those in the patent.

Reverting once more to the electrical control cam shaft 255 and contacts 35e and 35d, it is necessary to include these cam-operated contacts in the circuit of relay 141116 because this relay should be operated by the closing of the contacts 35h10 or 35117 only after the rst ball of a frame has been rolled. Shaft 255 and cam 35j open contacts 35e-35d after the rolling of the second ball and thus permit the normal operation of the machine after the second ball even if only pin #7 or pin #l0 is knocked down by the second ball and all the remaining pins are standing.

Gutter balls- It has been stated previously that the disclosed relay system prevents needless operation of the machine when the first ball is a gutter ball and when the first and second balls are both gutter balls. The above is accomplished with the aid of the presence relays, their second set of contacts and two gutter switches which also control the operation of relay 14116 in the manner described below.

The second set of contacts of the presence relays 351- 3510 are contacts 35C. All contacts 35C are normally closed as long as the pins are standing, and are connected in series with source 1411i), conductor 1405, winding 14h16, conductor 1414, contacts 35C, and two gutter ball switches 1415 and 1416, which are connected in series with contacts 35e and in parallel with respect to each other. Source 149i? supplies power to relay 1466 and energizes it when either the rst ball or the rst and the second balls are gutter balls. Accordingly, contacts 55C and gutter switches 1415 and 1416 control the operation of relay 14% which is normally de-energized because of the normally open position of the two gutter ball switches 1415 and 1416. Operation of clutch Ii-4,

therefore, is also prevented when the rst ball is a gutter ball and when the rst and the second balls are gutter balls.

FIGURES l5 and 16 illustrate the type of gutter ball switches 1415 and 1416 which are suitable for performing the function assigned to them by the relay system. FIG. 15 illustrates the positioning of the switches at the inner ends 15% and 1501 of the two gutters 15112 and 1553. The switches include collars 15114 and 1505 which are supported in an elevated position above the gutters by springs 1507 mounted in dash-pots 1506. The dashpots, fitted with suitable iluid, furnish sucient time delay to maintain the contacts 1415 closed for that period of time which is required for preventing energization of clutch l-4 after the gutter ball strikes pit switch Still and puts the relay system into operation for lone cycle of operation required either after the rst or the second balls of a frame.

From the description of the gutter ball circuits, it follows that it is made operative only if all the pins remain standing, all relays S51-3510 remain de-energized, and all contacts 35C remain closed. Opening of Yany contacts 35C, which takes place if any of the pins are knocked down, makes the gutter ball circuit ineffective, contacts 140651 remain closed, and the machine is allowed to operate in its usual manner, as described in Patent 2,559,274.

A single relay 14116 is used for controlling the operation of clutch l-4 by the gutter ball circuit described above and also by the #7 or #l0 pin circuit described previously. The two circuits are in parallel with each other and have independent contacts 35b and 35e on the presence relays 35. The gutter ball circuit is not affected by the operation of cam 35f and contacts 35e and 35d.

Clutch K-5.-ln the cyclev of the pinsetting machine disclosed in Patent 2,559,274, the operation of `the pin carrying grippers 68 of the transfer device N are moved by cam 12S back and forth once each cycleof the machine, as described in col. 10, lines 44-54. f As also described in col. 7, lines 26-40 of the patent, the movecam shaft 28.

19 ment of table T to and from the pin supporting bed of the alley for setting and/ or resetting pins is also effected by means of a cam 148 which is formed integrally with cam 128, both of these cams being mounted on a In order to preserve the function ot these two cams in the normal operation of the machine described in the patent and alsoadapt their functioning to the modied cycle disclosed here, an additional clutch K- has been mounted on shaft 28. This clutch,` and its solenoid winding 1488, are identical to clutchlK-4. The circuit of solenoid 1488 is identical to the circuit of solenoid 350 of clutch 4, the two solenoids being 'connected in parallel to conductor 1414. Therefore, the

two solenoids are operated at the same time and under vthe same conditions which produce the energization of Vsolenoid 366.

In view of the above, clutch K-4 may be used for not only clutching and declutching cam 74 to and from shaft 28, but also for clutching and declutching cams 128 and 148 to and from the same shaft.

Accordingly, the operation of the pin grippers e8 and the movement of table T is now also under control of the gutter ball circuit and #7 or #l0 pin circuit; i.e., it is under control of the presence relays 351-35m and gutter switches 1415 and 1416.

Pinfall signalling The presence relays S51-35m and their contacts 35a are also used for operating the pintall signalling lights 1 through 10, FIG. 14, corresponding to the pin positions 1 through 1G. In Patent 2,559,274, the pinfall signal lights are operated by means of respotting cups 112 which are provided with the switch actuating members 320 which are raised in respotting cups 112 and close contacts 321 and circuit 322-324. Closing of circuit 322-324 energizes'relay 326 which closes contacts 326a, 32%, and 326c. The closing of contacts 326a lights a signal lamp (1-10) corresponding to the position of the particular pin which remained standing. The pinfall signal relays 326 remain locked in for the remainder of the cycle, after which the light circuits are broken by the de-energization of relays 326 through the opening of cam ContactV 326e (not shown in FIG. 14 but shown in FIG. 4 of the patent) mounted on shaft 255. De-energization of relays 326 extinrguishes the pinfall signalling lights thus completing the pinfall signalling cycle for any given ball.

In the disclosed system, the information about the presence or absence of the pins is furnished by the presence relays 35 immediately after any particular pin is knocked down. When a pin is knocked down, the presence relay 35 corresponding to the knocked down pin becomes energized and contacts 35a, corresponding to con-- tacts 323 in the patent, become closed'and the corresponding relay 326 becomes energized. From thenA on, the operation of the pinfall signalling means described here is identical to that in the patent. Accordingly, while in the patent the pinfall signalling mechanism is operated by the respotting cup 112, in this case .the pinfall signalling mechanism is operated by the presence relays 35 directly. Therefore, the respotting cups 112 need not have any switches S-323 accordingto this invention since they are replaced by the contacts '55a and armatures 35d of the presence relays 35.

contacts 140619 of relay 1406 i From the prior description of the functions performed by relay 35, it follows that relay 35 prevents the operation of clutch Ii-4 when (a) only pin #7 or pin #10 is knocked down by the first ball, and (b) when the first tecting system including a plurality of electrical imped- `lines 45-50 of the patent.

-closed by cam 168 only when the table reaches itslow`- ermost or pin-engaging position, as explained in col. 7,

In order to preserve the normal functions of the machine, even when operation of clutch K4and lowering of 'table T does not take place because of the operation of relay 1486, relay 1486 porting positions, a standing pin detecting system comprising a plurality of capacitive transducers each constructed for positioning at a dierent one of the pin supporting positions of the alley bed, means for supplying alternating current to each of said transducers, and means for deriving from each of said transducers an output signal the amplitude of which depends upon the capacitance of the transducer from which the output signal is derived; and pin tall signalling means connected to be operated by said output signals for indicating the pin fall result of each ball of a frame rolled, said transducers being so constructed and arranged that, when said transducers are positioned atl the pin supporting positions of the alley bed below the surface thereof, the capacitance of each of said transducers is markedly different when a ,pin is standing at the pin supporting position at which the transducer is located than when the pin is absent.

2. in a lbowling alley installation including an alley bed having a plurality of pin supporting positions; a plurality of bowling pins each adapted to be disposed on the alley Vbed I'at one of said positions, each of said pins having an intions, and electrical circuit means operatively-connected lto said coils for continuously monitoring the inductive coupling between each of said coils and the corresponding inductive element of one of said pins; and pin tall signalling means operated by said detecting system for indicating Vthe pin fall result of each ball of a trame rolled.

3. Ina bowling alley installation, a bowling alley having a pin supporting bed and a plurality of pin supporting positions, a standing pin detecting system operatively associated with said positions of said bowling alley, said deance means, means for detecting a variation in impedance in said detecting system in response to the knocking down of a pin or pins normallyrstanding on the pin supporting bed, by each ball rolled down the alley against standing pins, and pin fall signalling means operated by said detecting system for indicating the pin fall result of each ball of a frame rolled, said pin fall signalling means including a plurality of signalling units, said impedance means each including a capacitive device mounted at one of said pin supporting positions in such manner as to pressent a markedly different capacitance when a pin is standing at said one position than when the pin is absent, said detecting system including means operative in response to a change in capacitance for operating selected ones of 4 said signalling units corresponding to the pin spot position of each standing pin.

References Cited in the tile of this patent UNTTED STATES PATENTS 2,014,306 Barker Sept. l0, 1935 2,228,293 Wurzbach Jan. 14, 1941 2,338,733 Patterson et al Ian. 11, 1944 2,492,182 Robinson Dec. 27, 1949 2,613,933 Johns et al, Oct. 14, 1952 2,628,698 Bauerschmidt Feb. 10, 1953 2,646,599 Nutzler July 21, 1953 2,697,605 Montootn et al. Dec. 21, 1954 2,782,406 Krakora Feb. 19, 1957 

1. IN A BOWLING ALLEY INSTALLATION, A BOWLING ALLEY HAVING A PIN SUPPORTING BED PROVIDING A PLURALITY OF PIN SUPPORTING POSITIONS, A STANDING PIN DETECTING SYSTEM COMPRISING A PLURALITY OF CAPACITIVE TRANSDUCERS EACH CONSTRUCTED FOR POSITIONING AT A DIFFERENT ONE OF THE PIN SUPPORTING POSITIONS OF THE ALLEY BED, MEANS FOR SUPPLYING ALTERNATING CURRENT TO EACH OF SAID TRANSDUCERS, AND MEANS FOR DERIVING FROM EACH OF SAID TRANSDUCERS AN OUTPUT SIGNAL THE AMPLITUDE OF WHICH DEPENDS UPON THE CAPACITANCE OF THE TRANSDUCER FROM WHICH THE OUTPUT SIGNAL IS DERIVED; AND PIN FALL SIGNALLING MEANS CONNECTED TO BE OPERATED BY SAID OUTPUT SIGNALS FOR INDICATING THE PIN FALL RESULT OF EACH BALL OF A FRAME ROLLED, SAID TRANSDUCERS BEING SO CONSTRUCTED AND ARRANGED THAT, WHEN SAID TRANSDUCERS ARE POSITIONED AT THE PIN SUPPORTING POSITIONS OF THE ALLEY BED BELOW THE SURFACE THEREOF, THE CAPACITANCE OF EACH OF SAID TRANSDUCERS IS MARKEDLY DIFFERENT WHEN A PIN IS STANDING AT THE PIN SUPPORTING POSITION AT WHICH THE TRANSDUCER IS LOCATED THAN WHEN THE PIN IS ABSENT. 